||01-28-2009 02:40 PM
I used some DAP sprayfoam to seal a gap on the house, running along the bottom of the siding. It crumbled into powder a few weeks later when I tried to pull a piece of it out. But, it was very cold outside when I sprayed it and I'm assuming that's why it crumbled. It did expand and set-up though.
One thing about the spray foam that I didn't see on the can is that you can't use it on surfaces that will reach 240 degrees F. I thought the Great Stuff Fire-Blocker would be alright to fill a penetration in the attic floor between the hot water heater exhaust pipe and the wood/drywall around it. I thought if it's a fire blocker, it can handle high heat. I used it for that and a few days later found out it can't be used on hot surfaces either. I was up there last night cutting it away from that hot pipe, the foam has been around the pipe for about 3 weeks or so. The foam that was directly in contact with the pipe was melted and looked like orange hard-candy. I had to use a metal putty knife to pry it off. The foam about 1/2" out from the pipe looked normal.